ISO 8728:2024
(Main)Ships and marine technology — Marine gyro-compasses
Ships and marine technology — Marine gyro-compasses
This document specifies the construction, performance, and type testing for gyro-compasses which are required by the International Convention for the Safety of Life at Sea (SOLAS), 1974 (as amended), Chapter V, Regulation 19. This document specifies the minimum requirements, the construction, performance, and type testing for gyro-compasses, which required to comply with the performance standards adopted by the IMO Resolution A.424(XI).
Navires et technologie maritime — Compas gyroscopiques à usage marin
General Information
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Standards Content (Sample)
International
Standard
ISO 8728
Fourth edition
Ships and marine technology —
2024-01
Marine gyro-compasses
Navires et technologie maritime — Compas gyroscopiques à
usage marin
Reference number
© ISO 2024
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ii
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 3
5 Construction requirements . 4
6 Performance requirements . . 5
6.1 Accuracy in latitudes up to 60° .5
6.1.1 Settling time .5
6.1.2 Settle point error .5
6.1.3 Settling time under operational conditions .5
6.1.4 Settle point error under general conditions .5
6.1.5 Residual error in correction.5
6.1.6 Effect of alteration of speed.5
6.1.7 Effect of alteration of course .5
6.1.8 Accuracy on a Scorsby table .5
6.1.9 Synchronization between the master compass and repeaters .6
6.2 Interface .6
6.3 Alert management .6
6.3.1 General .6
6.3.2 Power failure in the gyro-compass (“Power fail” alert) .6
6.3.3 Malfunction of the gyro-compass system (“System fault” alert) .7
7 Type tests . 7
7.1 General .7
7.2 Settling time test .7
7.3 Settle point error test .7
7.4 Settle point heading repeatability test .7
7.5 Settling time on a Scorsby table .7
7.6 Scorsby test.8
7.7 Intercardinal motion test .8
7.8 Repeater accuracy test .8
7.9 Speed correction test .9
7.10 General requirement test .9
7.10.1 General .9
7.10.2 Voltage variation test .9
7.10.3 Frequency variation test .10
7.10.4 Vibration tests .10
7.10.5 Temperature test . .11
7.10.6 Damp heat test . .11
7.10.7 Other tests .11
7.11 Interface test .11
7.12 Alert management test . 12
7.12.1 Basic test for alert management . 12
7.12.2 “ Power fail” alert or output of a status signal on the EUT power . 12
7.12.3 “System fault” alert . 12
8 Marking . .12
9 Information .12
Annex A (normative) Requirements for ship surveyors for the installation of gyro-compasses
and repeater compasses on board ships .13
iii
Annex B (normative) Alerts definition for gyro-compasses . 14
Annex C (normative) IEC 61162 interfaces for VDR and other external equipment .15
Bibliography . 17
iv
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
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with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
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This document was prepared by Technical Committee ISO/TC 8, Ships and marine technology, Subcommittee
SC 6, Navigation and ship operations.
This fourth edition cancels and replaces the third edition (ISO 8728:2014), which has been technically
revised.
The main changes are as follows:
— Clause 4 (abbreviated terms) has been added;
— in 6.3, requirements related to bridge alert management have been added;
— in 7.1, a requirement for display equipment has been added;
— in 7.12, test method for requirements related to bridge alert management has been added;
— in Annex B, the equivalent requirements in this document and IMO Resolution have been deleted and the
alerts with a standard alert identifier have been defined;
— in Annex C, IEC 61162 interfaces overview has been added;
— the normative references and bibliography have been updated.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
Introduction
This document is aligned with IMO Resolution A.424(XI) on performance standards for gyro-compasses.
Any text in this document which is a citation from the IMO Resolution A.424(XI), appears in italics. Within
these citations, any changes to the original wording of the IMO Resolution A.424(XI) are written in upright
font.
In this document, the following verbal forms are used:
— “shall” indicates a requirement;
— “should” indicates a recommendation;
— “may” indicates a permission;
— “can” indicates a possibility or a capability.
vi
International Standard ISO 8728:2024(en)
Ships and marine technology — Marine gyro-compasses
1 Scope
This document specifies the construction, performance, and type testing for gyro-compasses which are
required by the International Convention for the Safety of Life at Sea (SOLAS), 1974 (as amended), Chapter
V, Regulation 19.
This document specifies the minimum requirements, the construction, performance, and type testing for
gyro-compasses, which required to comply with the performance standards adopted by the IMO Resolution
A.424(XI).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
IEC 60945, Maritime navigation and radiocommunication equipment and systems — General requirements —
Methods of testing and required test results
IEC 61162-1, Marine navigation and radiocommunication equipment and systems — Digital interfaces - Part 1:
Single talker and multiple listeners
IEC 61162-2, Maritime navigation and radiocommunication equipment and systems — Digital interfaces — Part
2: Single talker and multiple listeners, high-speed transmission
IEC 61162-450, Maritime navigation and radiocommunication equipment and systems - Digital interfaces - Part
450: Multiple talkers and multiple listeners - Ethernet interconnection
IEC 62288, Maritime navigation and radiocommunication equipment and systems — Presentation of navigation-
related information on shipborne navigational displays — General requirements, methods of testing and required
test results
IEC 62923-1:2018, Maritime navigation and radiocommunication equipment and systems — Bridge alert
management — Part 1: Operational and performance requirements, methods of testing and required test results
IEC 62923-2, Maritime navigation and radiocommunication equipment and systems — Bridge alert management
— Part 2: Alert and cluster identifiers and other additional features
IMO Resolution MSC 302(87), Performance standards for bridge alert management
IMO Resolution MSC 191(79), Performance standards for the presentation of navigation-related information on
shipborne navigational displays
IMO Resolution MSC 466(101), Amendments to the performance standards for the presentation of navigation-
related information on shipborne navigational displays (Resolution MSC.191(79))
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
gyro-compass
complete equipment comprising all essential elements of the complete design, including both the gyro-
compass as heading sensor and the associated heading transmission system
[SOURCE: IMO Resolution A.424(XI), 2.1, modified — elements of complete design have been specified.]
3.2
true heading
horizontal angle between the vertical plane passing through the true meridian and the vertical plane passing
through the ship’s fore-and-aft datum line
Note 1 to entry: The true heading is measured from true north (000°) clockwise through 360°.
Note 2 to entry: When the gyro-compass equipment is not installed on board ship, this “true heading” is regarded as
the true heading of the lubber line. Where a gyro-compass has the facility of introducing a correction by moving the
lubber line, the correction is set for the local latitude.
[SOURCE: IMO Resolution A.424(XI), 2.2, modified — notes 1 and 2 to entry have been added.]
3.3
settled
stable situation when any three readings taken at intervals of 30 min are within a band of 0,7°, with the
compass level and stationary
Note 1 to entry: The settling time is the elapsed time between the time of switch-on at the initial heading error and the
third recording of the settle.
[SOURCE: IMO Resolution A.424(XI), 2.3, modified — note 1 to entry has been added.]
3.4
settle point heading
mean value of ten readings taken at 20 min intervals after the compass has settled (3.3)
[SOURCE: IMO Resolution A.424(XI), 2.4]
3.5
settle point error
difference between the settle point heading (3.4) and the true heading (3.2)
[SOURCE: IMO Resolution A.424(XI), 2.5]
3.6
error
difference between the observed value and the settle point heading (3.4)
[SOURCE: IMO Resolution A.424(XI), 2.6]
3.7
repeater compass
device that reproduces the master compass card at a remote location
3.8
bearing repeater compass
device that reproduces the master compass card for the purpose of taking bearings
3.9
compass card
graduated dial of the compass which indicates the measured direction of the meridian
3.10
latitude error
error (3.6) to which some gyro-compasses (3.1) are subject, the magnitude and sign of which depend upon
the local latitude
Note 1 to entry: Means are provided for correcting this error.
3.11
speed error
error (3.6) to which gyro-compasses (3.1) are subject, the magnitude and sign of which depend upon the
speed, course, and latitude of the ship
Note 1 to entry: Means are provided for correcting this error.
3.12
lubber line
index line situated on the body of a compass against which the compass heading is read
3.13
master compass
main compass unit which supplies the heading information to the repeaters and other navigational aids
3.14
Scorsby table
test machine which enables a platform to oscillate independently about three axes
Note 1 to entry: It is used to simulate the motion of a ship.
3.15
bridge alert management
BAM
overall concept for management, handling and harmonized presentation of alerts on the bridge
[SOURCE: IMO Resolution MSC.302(87), Appendix 1]
3.16
central alert management system
CAM system
combined functionality of the central alert management and the central alert management human machine
interface
[SOURCE: IMO Resolution MSC.302(87), Appendix 1]
4 Abbreviated terms
For the purposes of this document, the following abbreviated terms apply.
BAM bridge alert management
CAM central alert management
EUT equipment under test
GC gyro-compass
GNSS global navigation satellite system
SDME speed and distance measuring system
VDR Voyage Data Recorder
5 Construction requirements
Gyro-compass units shall conform to the following requirements.
a) In accordance with IMO Resolution A.424(XI), 6.1 and 8, the equipment shall be capable of continuous
operation under conditions of vibration, humidity, change of temperature and variations of the power supply
as specified in 7.10.2 to 7.10.6.
b) For ships which are required to carry bearing repeater compasses, the construction of these shall be as
follows.
1) The bearing repeater compass shall be designed to be fitted with an azimuth reading device.
2) A gimbal mechanism shall be provided to enable the bearing repeater compass card to be held
horizontally against the ship's motion.
3) Any bearing repeater compass intended for use on an open deck shall be waterproof.
c) In accordance with IMO Resolution A.424(XI), 3, the compass card shall be graduated at equal intervals of
1° or fraction thereof.
The graduation error shall be less than ±0,2°.
A numerical indication shall be provided at least at every 10°, starting from 000° clockwise through 360°.
d) In accordance with IMO Resolution A.424(XI), 4, fully adequate illumination shall be provided to enable
the reading of all compass cards at all times. Facilities for dimming shall be provided.
e) Both master compass and repeater compasses shall be provided with a lubber line to indicate the ship’s
heading.
The base or some other fixed extremity of the compass shall be marked or identified in such a way as
to facilitate the installation of the compass in a ship, so that the lubber line lies in a vertical fore-and-
aft plane of the ship. Where a gyro-compass has the facility of introducing a correction by moving the
lubber line, the correction during installation shall be set to zero. If such marks or identifications are
not in the same vertical planes as the uncorrected lubber line, then the horizontal angular relationship
between them shall be clearly indicated.
f) In accordance with IMO Resolution A.424(XI), 9.1, the master compass and any repeaters used for taking
visual bearings shall be installed or adjusted in a ship with their fore and aft datum lines parallel to the
ship's fore and aft datum line to within ±0,5°. The lubber line shall be in the same vertical plane passing
through the centre of the card of the compass and shall be aligned accurately in the fore and aft direction.
Requirements for ship surveyors for the installation of gyro-compasses and repeater compasses on
board ships shall be in accordance with Annex A.
g) In accordance with IMO Resolution A.424(XI), 9.2, means shall be provided for correcting the errors
induced by speed and latitude. Graphical or tabular means of correction can be used.
h) In accordance with IMO Resolution A.424(XI), 7.1, steps shall be taken to eliminate as far as is practicable,
the causes of, and to suppress, electromagnetic interference between the gyro-compass and other equipment
on board.
i) In accordance with IMO Resolution A.424(XI), 7.2, mechanical noise from all units shall be so limited as to
ensure the hearing of sounds on which the safety of the ship may depend.
j) In accordance with IMO Resolution A.424(XI), 9.7, the equipment shall be so constructed that it is readily
accessible for maintenance purposes.
k) In accordance with IMO Resolution A.424(XI), 6.2, means shall be incorporated for the protection of the
equipment from excessive currents and voltages, transients and accidental reversal of power supply polarity.
l) In accordance with IMO Resolution A.424(XI), 6.3, if provision is made for operating the equipment from
more than one source of electrical energy, arrangements for rapidly changing from one source of supply to
the other shall be incorporated.
m) In accordance with IMO Resolution A.424(XI), 9.4, the gyro-compass shall be designed to enable heading
information to be provided to other navigational aids. See 6.2.
6 Performance requirements
6.1 Accuracy in latitudes up to 60°
6.1.1 Settling time
In accordance with IMO Resolution A.424(XI), 5.1.1, when switched on in accordance with the manufacturer's
instructions, the compass shall settle within 6 h.
6.1.2 Settle point error
In accordance with IMO Resolution A.424(XI), 5.1.2, the settle point error at any heading shall not
exceed ± 0,75° × secant latitude, and the RMS value of the differences between individual heading indications and
the mean value shall be less than 0,25° × secant latitude. The repeatability of settle point error from one run-up
to another shall be within 0,25° × secant latitude.
6.1.3 Settling time under operational conditions
In accordance with IMO Resolution A.424(XI), 5.2.1, when switched on in accordance with the manufacturer's
...
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